Client crash via unchecked FastGlyph bitmap length
Published Jan 19, 2026 · Updated Jan 19, 2026
Heap-based buffer overflow in FreeRDP before 3.21.0 allows remote attackers controlling an RDP server to crash clients via a FastGlyph order. update_read_fast_glyph_order accepts the remaining stream length as cbData without checking the bitmap size implied by cx and cy, so freerdp_glyph_convert reads beyond the allocated glyph buffer. Exploitation requires a client connection to an attacker-controlled RDP server and interrupts only that client process; no data disclosure or modification is reported.
Summary
What happened
Heap-based buffer overflow in FreeRDP before 3.21.0 allows remote attackers controlling an RDP server to crash clients via a FastGlyph order. update_read_fast_glyph_order accepts the remaining stream length as cbData without checking the bitmap size implied by cx and cy, so freerdp_glyph_convert reads beyond the allocated glyph buffer. Exploitation requires a client connection to an attacker-controlled RDP server and interrupts only that client process; no data disclosure or modification is reported.
The record
- CVE
- CVE-2026-23732
- Published
- Jan 19, 2026
- Updated
- Jan 19, 2026
- Vendor
- FreeRDP
- Product
- FreeRDP
- Classifications
- CWE-122, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 19, 2026CVE publishedPublication date reported by the CVE source.
- Jan 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.21.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- FastGlyph AddressSanitizer crash proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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